Tk_CreateMainWindow(3Tk)Tk_CreateMainWindow(3Tk)NAME
Tk_CreateMainWindow, Tk_CreateWindow, Tk_CreateWindowFromPath,
Tk_DestroyWindow, Tk_MakeWindowExist - create or delete window
SYNOPSIS
#include <tk.h>
Tk_Window
Tk_CreateMainWindow(interp, screenName, baseName, className)
Tk_Window
Tk_CreateWindow(interp, parent, name, topLevScreen)
Tk_Window
Tk_CreateWindowFromPath(interp, tkwin, pathName, topLevScreen)
Tk_DestroyWindow(tkwin)Tk_MakeWindowExist(tkwin)ARGUMENTS
Tcl_Interp *interp (out) Tcl interpreter to use for error
reporting. If no error occurs,
then *interp isn't modified. For
Tk_CreateMainWindow, this
interpreter is associated
permanently with the created
window, and Tk-related commands
are bound into the interpreter.
char *screenName (in) String name of screen on which to
create window. Has the form
displayName.screenNum, where
displayName is the name of a
display and screenNum is a screen
number. If the dot and screenNum
are omitted, the screen number
defaults to 0. If screenName is
NULL or empty string, defaults to
contents of DISPLAY environment
variable.
char *baseName (in) Name to use for this main window.
See below for details.
char *className (in) Class to use for application and
for main window.
Tk_Window parent (in) Token for the window that is to
serve as the logical parent of the
new window.
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Tk_CreateMainWindow(3Tk)Tk_CreateMainWindow(3Tk)
char *name (in) Name to use for this window. Must
be unique among all children of
the same parent.
char *topLevScreen (in) Has same format as screenName. If
NULL, then new window is created
as an internal window. If non-
NULL, new window is created as a
top-level window on screen
topLevScreen. If topLevScreen is
an empty string (``'') then new
window is created as top-level
window of parent's screen.
Tk_Window tkwin (in) Token for window.
char *pathName (in) Name of new window, specified as
path name within application (e.g.
.a.b.c).
DESCRIPTION
The three procedures Tk_CreateMainWindow, Tk_CreateWindow, and
Tk_CreateWindowFromPath are used to create new windows for use in Tk-
based applications. Each of the procedures returns a token that can be
used to manipulate the window in other calls to the Tk library. If the
window couldn't be created successfully, then NULL is returned and
interp->result is modified to hold an error message.
Tk supports three different kinds of windows: main windows, internal
windows, and top-level windows. A main window is the outermost window
corresponding to an application. Main windows correspond to the
independent units of an application, such as a view on a file that is
part of an editor, or a clock, or a terminal emulator. A main window is
created as a child of the root window of the screen indicated by the
screenName. Each main window, and all its descendants, are typically
associated with a single Tcl command interpreter. An internal window is
an interior window of a Tk application, such as a scrollbar or menu bar
or button. A top-level window is one that is created as a child of a
screen's root window, rather than as an interior window, but which is
logically part of some existing main window. Examples of top-level
windows are pop-up menus and dialog boxes.
Tk_CreateMainWindow creates a new main window and associates its interp
argument with that window and all its eventual descendants.
Tk_CreateMainWindow also carries out several other actions to set up the
new application. First, it adds all the Tk commands to those already
defined for interp. Second, it turns the new window into a toplevel
widget, which will cause the X window to be created and mapped as soon as
the application goes idle. Third, Tk_CreateMainWindow registers interp
so that it can be accessed remotely by other Tk applications using the
send command and the name baseName. Normally, baseName consists of the
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Tk_CreateMainWindow(3Tk)Tk_CreateMainWindow(3Tk)
name of the application followed by a space and an identifier for this
particular main window (if such an identifier is relevant). For example,
an editor named mx displaying the file foo.c would use ``mx foo.c'' as
the basename. An application that doesn't usually have multiple
instances, such as a clock program, would just use the name of the
application, e.g. ``xclock''. If baseName is already in use by some
other registered interpreter, then Tk_CreateMainWindow extends baseName
with a number to produce a unique name like ``mx foo.c #2'' or ``xclock
#12''. This name is used both as the name of the window (returned by
Tk_Name) and as the registered name of the interpreter. Fourth,
Tk_CreateMainWindow sets className as the class of the application (among
other things, this is used for lookups in the option database), and also
as the class of the main widget.
Either internal or top-level windows may be created by calling
Tk_CreateWindow. If the topLevScreen argument is NULL, then the new
window will be an internal window. If topLevScreen is non-NULL, then the
new window will be a top-level window: topLevScreen indicates the name of
a screen and the new window will be created as a child of the root window
of topLevScreen. In either case Tk will consider the new window to be
the logical child of parent: the new window's path name will reflect
this fact, options may be specified for the new window under this
assumption, and so on. The only difference is that new X window for a
top-level window will not be a child of parent's X window. For example,
a pull-down menu's parent would be the button-like window used to invoke
it, which would in turn be a child of the menu bar window. A dialog box
might have the application's main window as its parent. This approach
means that all the windows of an application fall into a hierarchical
arrangement with a single logical root: the application's main window.
Tk_CreateWindowFromPath offers an alternate way of specifying new
windows. In Tk_CreateWindowFromPath the new window is specified with a
token for any window in the target application (tkwin), plus a path name
for the new window. It produces the same effect as Tk_CreateWindow and
allows both top-level and internal windows to be created, depending on
the value of topLevScreen. In calls to Tk_CreateWindowFromPath, as in
calls to Tk_CreateWindow, the parent of the new window must exist at the
time of the call, but the new window must not already exist.
In truth, the window-creation procedures don't actually issue the command
to X to create a window. Instead, they create a local data structure
associated with the window and defer the creation of the X window. The
window will actually be created by the first call to Tk_MapWindow.
Deferred window creation allows various aspects of the window (such as
its size, background color, etc.) to be modified after its creation
without incurring any overhead in the X server. When the window is
finally mapped all of the window attributes can be set while creating the
window.
The value returned by a window-creation procedure is not the X token for
the window (it can't be, since X hasn't been asked to create the window
yet). Instead, it is a token for Tk's local data structure for the
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Tk_CreateMainWindow(3Tk)Tk_CreateMainWindow(3Tk)
window. Most of the Tk library procedures take Tk_Window tokens, rather
than X identifiers. The actual X window identifier can be retrieved from
the local data structure using the Tk_WindowId macro; see the manual
entry for Tk_WindowId for details.
Tk_DestroyWindow deletes a window and all the data structures associated
with it, including any event handlers created with Tk_CreateEventHandler.
In addition, Tk_DestroyWindow will delete any children of tkwin
recursively (where children are defined in the Tk sense, consisting of
all windows that were created with the given window as parent). If tkwin
was created by Tk_CreateInternalWindow then event handlers interested in
destroy events are invoked immediately. If tkwin is a top-level or main
window, then the event handlers will be invoked later, after X has seen
the request and returned an event for it.
If a window has been created but hasn't been mapped, so no X window
exists, it is possible to force the creation of the X window by calling
Tk_MakeWindowExist. This procedure issues the X commands to instantiate
the window given by tkwin.
KEYWORDS
create, deferred creation, destroy, display, internal window, main
window, register, screen, top-level window, window
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